Water tube coil steam generating apparatus



May 9, 1950 P. ARANT WATER TUB'E COIL STEAM GENERATING APPARATUS Filed Jan. 22, 1947 2 Sheets-Sheet l 20 H'r' y [ran Z May 9, 1950 P. ARANT 2,507,293

WATER TUBE COIL STEAM GENERATING APPARATUS Filed Jan. 22. 1947 2 Sheets-Sheet 2 A 1322717 flran f Patented May 9, 1950 WATER TUBE COIL STEAM GENERATING APPARATUS Perry Arant, Alhambra, Califi, assignor to Clayton Manufacturing Company, Alhambra, Calif., a corporation of California Application January 22, 1947, Serial No. 723,524

7 Claims.

The present invention relates to steam generating apparatus and more particularly to a steam generating coil for use in such apparatus.

More specifically, the steam generating coil of the present invention comprises a double wound water wall section including two interwound upright helical pipe coils extending for substantially the full height of the steam generating unit, and a steam generating or main heating section comprising two groups of pancake-type pipe coils connected in series and arranged within the water wall section and extending downwardly therein to a zone substantially medially of the height of said water wall section. The double wound water wall section may be made by the method disclosed and claimed in my co-pending application Serial No. 688,720, filed on August 6, 1946, and entitled Heating coil and method of making same. The space within the water wall section below the pancake coils provides a combustion chamber whose side wall is lined with a sheet metal liner of the kind disclosed and claimed in my co-pending application Serial No. 688,721, filed on August 6, 1946, and entitled Steam generating apparatus.

The principal object of the invention is to provide a steam generating unit which is extremely compact, but nevertheless capable of developing a given high boiler horsepower without sacrificing efficiency and economy.

Another object of the invention is to provide a steam generating coil constructed so that it will prevent substantial local separation of the liquid and vapor within the coil, which, under certain conditions of operation, produces a thermal cycle or coil priming conducive to surging or spasmodic discharge from the coil.

Another object of the invention is to provide a steam generating coil constructed so as to minimize friction flow losses as the liquid is expanded by heat, and as the result of the presence of some vapor in the liquid, as the liquid approaches the discharge end of said coil.

Still another object of the invention is to provid a steam generating coil including a water wall section arranged so that fluid can be discharged therefrom into the main heating section of said coil without the use of any external risers.

Other objects and advantages of the invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

Fig. 1 is a longitudinal sectional view through a steam generating unit containing a coil em- .bodying th principles of the present invention;

r the casing 4.

Fig. 2 is a fragmentary perspective view of the pper portion of the water wall section of the coil; and

Fig. 3 is a perspective view of the lower portion of the water wall section of the coil, particularly illustrating the return bend connection for establishing reverse flow of fluid through said water wall section.

Referring now more particularly to Fig. 1 of the drawings, the numeral I generally identifies the steam generating unit, which includes a housing 2 made up of a base 3, jacket or casing sections 4 and 4 and a top 5, all secured together in any suitabl or conventional manner. The housing 2 is supported by a plurality of legs 6 disposed below the base 3.

The base 3 includes a wall I provided with a central air opening 8 through which th upper end of a burner or fuel supply device 9 is adapted to extend. .An air supply duct I0 is disposed below the wall 7 and is arranged to deliver air from a blower (not shown) to an air supply chamber I l surrounding the fuel supply device 9.

The bas 3 includes a wall I2 spaced from the wall 1 by a plurality of air deflecting baflles 93, the arrangement of which is unimportant for the present disclosure, but which is set forth in detail in my co-pending application Serial No. 688,720, supra. The wall I2 is provided with a central opening I4 having an annular bushing i5 mounted therein. The opening in the bushing I5 is concentric with the opening 8 and establlshes communication between the air supply chamber II and a combustion chamber I6 within A ring i1 is welded or otherwise secured to the wall 12 and the portion of said wall between said ring and the bushing I5 is lined with. suitable refractory material I8 serving as the bottom of the combustion chamber IS.

The fuel supply device 9 includes a pair of fuel oil atomizing nozzles is for introducing atomized fuel into the combustion chamber It. A pipe #20 is connected to the device 9 for supplying fuel thereto, and electrode means 2| is arranged adjacent the nozzles IS to ignite the atomized fuel. It will be understood, of course, that air to support combustion is supplied to the combustion chamber I5 simultaneously with the supply of fuel, through the air duct I0, supply chamber II, etc.

The steam generating coil is generally identifled by the numeral 22 and includes a double wound water wall section 23 preferably consisting of two predetermined lengths of helical pipe 24 and 25 interconnected at their lower ends 'stitutin the heating section 23 by a generally U-shaped return bend 25. The method of winding a double coil similar to the water wall section 23 is set forth in my copending application Serial No. 688,720, supra.

The steam generating coil 22 also includes a steam generating or main heating section. 23 disposed within the water wall section and comprising two groups of spirally wound pancake-type pipe coils generally identified by the numerals 21 and 28, respectively, the first or upper group of pancake coils consisting of, for example, eight pancake sections and having a depth indicated by the dimension A, and the second or lower group of pancake coils consisting of, for example, five pancake sections and having a depth indicated by the dimension B. The pipe wound to form the pancake coils 23 is larger in diameter than that employed in. the pancake coils 21, for reasons explained later. The combined depth of the two groups of coils, as indicated by the dimensions A and B, is approxirnately equal to half the height of the water wall section 23.

The upper end 28 of the helical coii of the water wall section 23 serves as an inlet and has a water supply pipe 38 connected thereto. The upper end 3! of the other helical pipe of the water wall section 23 is connected to the inlet end 32 of the top pancake coil of the group of coils occupying the space dimensioned A. All of the pancake coils 2! are connected for series flow of fluid therethrough, and the outlet end of the lowermost pancake coil 2? is connected with the inlet end 34 of the uppermost pancake coil 28. All of the pancake coils 28 of the occupying the space dimensioned B are ai n connected for series flow of the fluid and the outlet end 35 of the bottom pa 28 is connected to one end 35 of a discharge conduit 3?, which extends upwardly through the core of the entire stack of pancake coils con- A discharge pipe 38 is connected with the upper end of the discharge conduit 31.

In constructing the steam generating coil the pipes 24 and 25 of the Water wail section 23 are wound in helical form in such manner that the adjacent coils preferably contact each other. The pancake coils 2? and 28 are preassembled and connected in series and uppermost pancake coil 2'! is welded to supporting bars 353 having a loop 66 secured thereto to enable the assembly to be handled by a crane and lowered into nesting position within the water wall section 23. The outlet 3! of the water wall section 23 and the inlet 32 of the top pancake coil 27 of the heating section 23 are welded together after these sections are nested. Brackets ll secure the ends of the bars as to an upper shell section 42 which partially overlaps the upper end of the casing 4 and is welded thereto. The casing sec tions 4 and 42 are surrounded by suitable heat insulating material 43.

All of the pancake coils 2'! and 28 of the heating section 23 are spaced apart vertically to permit the free flow of the hot gases of combustion thereover, bafiles 44 bein arranged at the lower portion of said heating section to prevent the direct passage of the combustion gases from the combustion chamber is through the core formed at the central portion of said heating section. A stack 45 is connected with the top of the housing 2 above said core.

A stainless steel sheet metal liner d5 of the character described in detail in my co-pending 3 application, Serial No. 688,721, supra, is disposed in the combustion chamber I 6 in telescopic relation with the ring l1, and extends from the wall I 2 to a zone occupied by the lowermost pancake coil 28 of the heating section 23.

The liner 46 has its outer periphery in contact with the inner surface of the surrounding, coils of the water wall section 23 and serves as a side wall for the combustion chamber IS. The liner l5 conducts heat directly to approximately the lower half of the water wall section 23 in contact therewith, the heat being rapidly transferred to the liquid in the water wall section 23 at a rate sufiicient to prevent burning out or undue heating of the liner 46.

The operation of the steam generatin unit I is as follows:

The liquid to be heated is supplied through the pipe 30 to the inlet end 29 of the helical pipe 24 of the water wall section 23 and said liquid flows downwardly through the coils provided by said pipe. The direction of flow of the liquid through the water wall section 23 is reversed at the return bend 25 and then flows up- Wardly through the coils of the helical pipe 25 and ultimately discharges through the outlet end 3! thereof into the inlet end 32 of the to pancake coil 2'! of the main heating section 23 The construction of the water wall section 23 and the liner 48 is such that a substantial amount of heat is absorbed by the liquid in the water wall section 23 so that it is preheated before it enters the top pancake coil 21. By virtue of the dual helical coil arrangement in the water wall section 23, it will be apparent that the direction of flow of the fluid is opposite in any two adjacent coils thereof, and also that the incoming fluid in the coil 24 travels in a direction counter to that or the flow of the combustion gases while the fluid flow in the coil 25 is in the same direction as that of the gases. However, the flow of the fluid is again reversed when it enters the pancake coils of the main heating section 23 In other words, the direction of flow of fluid through the pancake coils 2'! and 28 is counter to that of the travel of the gases of combustion, with the result that the fluid in said heating section is subjected to the hottest gases in the combustion chamber it just prior to its entry into the discharge conduit 37.

It will be noted from Fig. 1 that the diameter of the pipe employed in making the upper group of pancake coils 2! is of the same size as the pipe in the water Wall section 23, and that the pipe employed in making the lower group of pancake coils 28 is larger than that .of the pipe employed in making said water wall and upper group or pancake coils. As an example of one operative embodiment of the present invention, a horsepower boiler preferably employs pipe 1 inch in diameter for making the Water wall section 23 and the upper group of pancake coils 27, whereas the diameter of the pipe employed in making the lower group of pancake coils 28 is preferably 1 /2; inches. The object of making the pancake coils 28 of larger diameter .pipeis to provide additional space or volume at the outlet end of the heating section 23 to compensate for the thermal expansion of the liquid and for the presence of vapor in said liquid, to thereby reduce losses due to friction flow, and to avoid the collection of vapor in slugs, which are jointly conducive to retarded flow and cause non-uniform or spasmodic discharge of the fluid from the unit.

It will be understood that both the water well section 23 and the main heating section 23 may include as many coils as are necessary to meet the requirement of a desired installation, and that the particular number of coils shown in the drawings and mentioned in the specification is erely by way of illustration of one operative embodiment of the invention and not by way of limitation.

It will also be understood that various changes may be made in the construction and arrangement of the parts comprisin the present steam generating unit without departing from the spirit of the invention or the scope of the annexed claims.

I claim:

1. A heating coil, comprising: a water wall section including two upright helical coils of pipe having their turns intermeshed and their lower ends interconnected by a return bend, the upper end of one of said helical coils serving as an inlet; a heating section including a plurality of spirally wound, superposed pancake-type pipe coils connected in series, the upper end of the other helical coil of said water wall section being connected to the top pancake coil of said heating section; and a discharge conduit connected to the bottom pancake coil of said heatin section.

2. A heating coil, comprising: a water wall section including two upright helical coils of pipe having their turns intermeshed and their lower ends interconnected by a return bend, the upper end of one of said helical coils serving as an inlet; a heating section disposed within the upper portion of said water wall section and including a plurality of spirally wound, superposed pancake-type pipe coils connected in series, the upper end of the other helical coil of said water wall section being connected to the uppermost pancake coil of said heating section; and a. discharge conduit connected to the lowermost of said pancake coils of said heating section.

3. A heating coil as defined in claim 2, in which the height of the pancake coil heating section is approximately half the height of the water wall section.

4. A heating coil, comprising: a water Wall section including two upright helical coils of pipe having their turns intermeshed and their lower ends interconnected by a return bend, the upper end of one of said helical coils servin as an inlet; a heating section disposed within the upper portion of said water wall section and includin an upper group and a lower group of spirally wound, superposed pancake-type coils connected in series, the upper end of the other helical coil of said water wall section being connected to the top pancake coil of said upper group of pancake coils, the lower group of pancake coils consisting of pipe of a larger diameter than that of the upper group of pancake coils to compensate for expansion of the liquid being heated and for the presence of vapor therein and thereby avoid surging or spasmodic discharge therefrom; and a discharge conduit connected to the bottom pancake coil of said lower group of pancake coils.

5. Steam generating apparatus, comprising: a housing including a base, a side wall casing, and a top; and a steam generating coil comprising a double wound water wall section having an inlet and an outlet at the upper end thereof, said water wall section being disposed within said casing and extending substantially for the full height of said casing, and a heating section comprising a plurality of superposed pancake coils arranged within said water wall section and having the uppermost pancake coil thereof connected to the outlet of said water wall section, the lowermost pancake coil being spaced from said base to provide a combustion chamber.

6. Steam generating apparatus, comprising: a housing including a base, a side wall casing, and a top; a steam generating coil comprising a double wound Water Wall section having an inlet and an outlet at the upper end thereof, said water wall section being disposed within said casing and extending substantially for the full height of said casing, and a heating section comprising a plurality of superposed pancake coils arranged within said water wall section and having the uppermost pancake coil thereof connected to the outlet of said water wall section, the lowermost pancake coil being spaced from said base to provide a combustion chamber, said base having an air inlet opening communicating with said combustion chamber; refractory material on said base surrounding said air inlet opening; and a heat conducting liner in said combustion chamber disposed between said refractory material and the lowermost pancake coil of said heating section and having its outer periphery in contact with said water wall section.

7. Steam generating apparatus, comprising: a housing including a base, a side wall casing, and a top; a steam generating coil comprising a double wound water wall section having an inlet and an outlet at the upper end thereof, said water wall section being disposed within said casing and extending substantially for the full height of said casing, and a heating section comprising a plurality of superposed pancake coils arranged within said water wall section and extending downwardly into said water wall section to a zone substantially medially of the height of said water wall section to provide a combustion chamber below said heating section, said heating section having the uppermost pancake coil thereof connected to the outlet of said Water wall section, said base having an air inlet opening communicating with said combustion chamber; refractory material on said base surrounding said air inlet opening; and a sheet metal liner in said combustion chamber disposed between said refractory material and the lowermost pancake coil of said heating section and having its outer periphery in contact with said water wall section.

PERRY ARANT.

REFERENCES CITED The following references are of record in the file of this patent:

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